Thermo-dynamic reciprocating apparatus



Sept. 6, 1960 R. J. MEIJER THERMO-DYNAMIC RECIPROCATING APPARATUS Y .fill/falliti!!! A ,n "l III I FIG.2

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INVENTOR ROELFJAN MEIJER ENT United States Patent vTHERMO-DYNAMIC RECIPROCATING APPARATUS Roelf Jen Meijer, Eindheven, Netherlands, assigner to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Oct. 3, 1957, Ser, No. 687,910

Claims priority, application Netherlands Get. 9, 1956 3 Claims. (Cl. 60-24) This invention relates to thermo-dynamic reciprocating apparatus 4comprising piston like members reciprocating with -a relative phase diiference, only one face of a piston like member inuencing the volumetric capacity of the -work chamber of the apparatus, which apparatus comprises a crankcase wherein the pressure during operation is lower than the minimum pressure of the cycle performed in the apparatus. The term thermo-dynamic reciprocating apparatus is to be understood to include hot-gas engines, refrigerators and heat pumps, the lastmentioned two types of apparatus operating according ,to the reversed hot-gas engine principle. j Such apparatus may be a displacer apparatus, in which one of the piston like members is la displacer and the other piston like member inuences the work chamber only with one face. Alternatively, the apparatus may comprise two pistons each inuencing the work space of the apparatus only with one face, the apparatus being V-shaped or the two pistons being movable parallel to one another.

In such apparatus, it is known to ill the crank case and vthe work space of the apparatus with the same gas, while the pressure in the crank-case is at least equal to the minimum pressure of the cycle and in many cases equal to the average pressure of this cycle, so that the rod forces of the driving gear are smaller than in the case of atmospheric pressure prevailing in the crank case, hence the driving gear may be lighter.

If, however, the average pressure of the cycle is chosen higher than has hitherto been usual and is, for example, 10() atmospheres, and if the size of the apparatus is also made larger, the forces exerted on the wall of the crank case are considerable so that special and complicated wall constructions have to be devised.

According to the invention, this disadvantage is avoided by causing the other face of the piston-like member to influence the volumetric capacity of an auxiliary space located between the work space and the crank case, in which auxiliary space the pressure during operation of the apparatus is at least equal to the minimum pressure of the cycle performed in the apparatus.

In this construction, consequently, a low pressure may prevail in the crank-case, so that it need not have extremely heavy walls, while the driving gear may notwithstanding that be light-weight as la result of the presence of the auxiliary space.

For structural reasons it is desirable for the piston rod of the piston-like member exclusively to make a rectilinear reciprocating movement. Therefore, this rod might be provided with a cross-head reciprocating in the crank case.

If however, the apparatus is a displacer apparatus, it is particularly advantageous to use a different construction with a view to reducing the height of the apparatus. According to the invention, the piston is connected, through two equal connecting rods located symmetrically one at each side of a plane extending through the centre Patented sept. e, rseo line of the cylinder, to two equal cranks forming part of two crank shafts provided with balance weights. These crank shafts rotate synchronously relatively to one another, in phase and in `opposed senses and their centre lines extend relatively parallel and symmetrically one at each side of said plane through the centre line of the cylinder in a plane extending at right angles to the plane through the centre line of the cylinder of the apparatus, while the displacer is directly or indirectly coupled to the cranks through two displacer connecting rods which are likewise located symmetrically relative to the plane through the centre line of the cylinder.

In order that the invention may be readily carried into effect, an example will now be described in detail with reference to the accompanying drawing in which:

Fig. 1 is a vertical section of the apparatus, and Fig. 2 is a horizontal section on the line II-II of Fig. 1. e e

The apparatus comprises a cylinder 1 in which a displacer 2 yand a piston 3 are `adapted to reciprocate.

The displacer 2 varies the volumetric capacity of a space 4 which communicates through a heater 5, a regenerator 6 and a cooler 7 to a space 8 located between 11 of the apparatus comprises the heater 5 and is secured by means of bolts 12 to a jacket 13 containing the cooler 7. The jacket 13 is secured by means of bolts 14 to a crank case 15 of the apparatus. Below the piston 3, provision is made of a space 16 which is separated from the crank case by means of a wall 17. This wall 17 has a bore 18, through which passes a hollow piston rod 19 of the piston, while a displacer rod 20 of the displacer is movable upwards `and downwards inside the hollow piston rod. The space 16 communicates with a space 22 by way of conduits 21.

Two heads 24 of two connecting rods 25 are rotatable about ashaft 23 which is iixedly secured to the piston rod 19, while the displacer rod 20 iixedly secured to the displacer is passed through the shaft 23. The connecting rods 25 further comprise two heads 26 which are rotatable labout crank pins 27. Ball-bearings are provided between the heads 26 and the cr-ank-pins 27. The heads 26 comprise projecting parts 28 with pins 29 about which two displacer connecting rod heads 30 are rotatable. At the other ends of the displacer connecting rods 31, provision is made of heads 32 both of which are adapted to rotate about a shaft 33 which is ixedly secured to the displacer rod 20. The crank pins 27 are eccentrically mounted on shafts (not represented) which are vcoupled together through tooth gears 34 and to which balance weights 35 vare screwed. The crank case 15 comprises a lid 36 at its lower end.

The masses of the piston connecting rods 24, the piston rod 19 'and the piston 3 substantially correspond to the masses of the displacer connecting rods 31, the displacer rod 20 and the displacer 2, while the length of each piston connecting rod 24 approximately corresponds to that of the displacer connecting rod 31. The process of compression and expansion during one revolution of cranks may be described by the following four phases.

Phase 1.--The Working medium is contained mainly in the cooled compression space 8 where it is compressed by a main piston 3 to the maximum pressure.

Phase 2.-'I`he displacer 2 moves the compressed gas from the compression space 8 to the hot expansion space 4 through cooler 7, regenerator 6, and heater 5. The

heat of compression is carried off by the cooler 7. The gas is heated by the passage through regenerator 6.

Phase 3.-The gas is expanded in hot space 4 and the heat produced is transferred to heater 5. This is accomplished by the simultaneous downward movement of the piston 3 and the displacer 2.

Phase 4,-The hot gas is driven back to the compression space 8 by the return motion ofthe displacer 2 in an upward direction. The working medium gives oi heat to the regenerator which was absorbed during the second phase.

In thepresent example, the apparatus' according to the invention is lled with hydrogen, the average pressure of which is 100 atmospheres during the cycle. For constructional reasons, the pressure inside the crank case should be considerably lower, for example correspond to atmospheric pressure, `and it may further be desirable not to ll the crank case with hydrogen. Unless taking special steps, however, the connecting rod forces and the bearing loads of the driving gear then would be very high.

Therefore, the space 16 is filled with hydrogen at a pressure at least corresponding to the minimum pressure during the cycle and, for example, in the present example, corresponding to the average pressure. The space 16 may also be provided in apparatus comprising driving 4gears of diierent type, for example a normal crank connecting-rod mechanism. However, the invention may be used with particular advantage in the driving gear as represented, more especially since the latter comprises a simple straight guide for the piston rod and the displacer rod. Therefore, the auxiliary space 16 functions to relieve the pressure on the crankcase due to the differential in pressures existing in the cylinder and the crankcase.

What is claimed is:

l. A thermo-dynamic reciprocating apparatus comprising a cylinder in which a closed thermodynamic cycle is performed by a gaseous medium, a piston and displacer adapted for reciprocation in said cylinder, said piston being provided with a bore extending axially of said cylinder, a crankcase connected to said cylinder, a wall between said cylinder and said crankc-ase, said wall having a bore therein extending axially of said cylinder, a pair of cranks within said crankcase, rst rod means connecting said piston with each of said cranks, second rod means connecting said displacer with each of said cranks whereby said piston and displacer are connected in outof-phase relationship, an auxiliary space provided with a gas therein and located between said wall and said piston whereby the reciprocation of said piston yalternately expands and contracts said gas to thereby counteract the pressures existing in said cylinder and to relieve the crankcase from relatively heavy pressure thereon.

2. A thermo-dynamic reciprocating apparatus comprising a cylinder in which a closed thermodynamic cycle is performed by a gaseous medium, a piston and displacer adapted for reciprocation in said cylinder, said piston being provided with `a bore extending axially of said cylinder, a crankcase connected to said cylinder, a wall between said cylinder and said crankcase, said Wall having a bore therein extending axially of said cylinder, a pair of cranks within said craukcase, two piston connecting rods connecting said piston with each of said cranks, two displacer connecting rods connecting said displacer with each of said rods and being substantially the same length as said piston connecting rods, one of said piston connecting rods and an adjacent displacer rod Ibeing located at one side of the central axis of said cylinder whereas the other piston connecting rod and the o ther displacer connecting rod is located at the other side of the central axis of the cylinder whereby said piston and displacer are connected in out-of-phase relationship, an auxiliary space provided with a gas therein and located between said wall and said piston whereby the reciprocation of said piston alternately expands and contracts said gas to thereby counteract the pressures existing in said cylinder and to relieve the crankcase from relatively heavy pressure thereon, one face of said piston influencing the volumetric capacity of said cylinder While the `other face of said piston inuencing the volumetric capacity of said auxiliary chamber.

3. A thermo-dynamic reciprocating apparatus comprising a cylinder in which a closed thermodynamic cycle is performed by a gaseous medium, la piston. and displacer adapted for reciprocation in said cylinder, said piston being provided with a bore extending axially of said cylinder, a crankcase connected to said cylinder, said crankcase having an operative pressure which is lower than the minimum pressure of the cycle performed in the cylinder of the apparatus, a wall between said cylinder and said crankcase, said wall having 4a bore therein extending axially of said cylinder, a pair of cranks within said crankcase, first rod means connecting s'aid piston with each of said cranks, second rod means connecting Asaid displacer with each of said cranks whereby said pis- References Cited in the file of this patent UNITED STATES PATENTS 1,240,862 Lundgaard Sept. 25, 1917 2,083,808 Andrews June 15, 1937 2,794,315 Meijer .lune 4, 1957 2,885,855 Meyer May 12, 1959 FOREIGN PATENTS 197,962 Great Britain Sept. 22, 1924 729,941 Great Britain May 11, 1955 

